Die holder cap



J. WATSON DIE HOLDER CAP June 10, 1952 Filed March 4, 1950 INVENTOR.John Woison.

ATTORNEY Patented June 10, 1952 Green field, Mass, a corporation ofMassachusetts Applicatiorrllil arch 4, 19th,

1 Claim. 1

This invention relates to thread-cutting dies and more particularly tothe die mounting for threading at high rotative speeds.

An object of the invention is to provide a die mounting which will besimple in form, inexpensive in manufacture and light and efiicient inoperation.

A further object of the invention is to provide a special form of dieholder cap for a die having a tapered slotted end.

Further objects of the invention, particularly in the formation of athree point support for a holder cap plate, will appear from thefollowing specification taken in connection with the accompanyingdrawings in which Fig. 1 is a plan view of the die and holder;

Fig. 2 is a sectional view of the die and holder along line 2-2 of Fig.1;

Fig. 3 is a perspective view of the cap; and

Fig. 4 is a sectional view of the cap along line 44 of Fig. 3.

Referring to the drawings, there is shown a threading device comprisinga die holder H], a die II, a die holder cap [2, and a lock nut I3. Thedie holder Ill has a threaded portion [4 and a shank portion l5.Diametrically opposed lugs IB are provided on the holder H] to engagethe grooves I! in the inner face l8 of the die II.

The die I I is provided with prongs or lands 2!], threads 2], and outerconical surfaces 22 terminated by the outer face 23. The inner face I8seats against the end surface IQ of the holder l0. The cap l2 comprisesa cap holder plate 25 and cap holder base 26. The base 26 is hexagonalin shape and has threads 21 adapted to engage the threads 28 to hold thecap I2 on the holder 10. The holder plate 25 is of a triangular shapewith a circular opening centered in the middle. The opening has acylindrical wall portion 32 and conical walls 33 and 34. The conicalwall portion 33 is at a lesser angle with the axis of the tool than theconical wall 34. The conical wall 33 engages the conical surfaces 22holdin the die on the holder. The angle of taper of the conical walls 22is less than the angle of the wall 34. Therefore the wall 33 contactsthe surfaces 22 along the surface adjacent the edge 35 and the innerportions of the surfaces are slightly separated. The holder plate isrigidly secured to the holder base 26 by the equally-spaced posts 38 ineach corner of the triangular shape forming a three element connectionbetween the inner and outer members. The posts 38 comprise a spacer 39and rivet 40. The spacer 39 is tubular in shape preferably cylindrical.The rivet 40 has a head 4| positioned in a seat 42 in the outer portionI2 and a shaft 43 extending through openings 44 in the rim of theportion [2, the tubular portion 39, through the opening 45 in the innerportion. The end of the rivet is peened over and forced into the seat 4!tightly holding the inner and outer members against the spacers 39. Thesurface 50 of the rim is below the surface of the opening with a bevel5| between them. The posts 38 are widely spaced with large spacesbetween them for the discharge of the chips and cooling medium, keepingthe cutting threads clean of the cuttings. The lock nut I3 is tightenedagainst the inner portion of the cap to lock the cap in place andpreventing it from loosening.

At high speed operation, the torque of the shank I5 is transmitted tothe lug H at the die end and directly to the sides of the slot of thedie itself so that the holder parts are carried around with the shanksubstantially torque-free.

The sole or main function of the cap parts is to accurately center thedie jaws in adjusted position, the exerted force of the holder being aninward pressure on the outer tapered surfaces of the die. This pressureis converted substantially entirely to tension between the holder plate25 and the holder base 26 and in the construction of this invention istransmitted through the three posts 38 which are assembled and headedover tightly to subject them to an initial tension snugly holding theholder plate 25 against the ends of the spacers 39 and so placing thesespacers under initial compression. In this way the entire cap structureis made a unitary piece with no play or looseness between the partswhich are relatively light and the complete assembly provides wide-openspaces discharging the chips outward from the die freely and. with notendency to obstruct or pack the material within the holder parts.

A three point support is provided for the head plate and thisautomatically accurately supports the end plate by three points whichnecessarily fall Within a predetermined plane giving a precise anddependable positioning and permanent sustaining of the head platetightly against the die surfaces in all positions of adjustment and use.

The supporting posts are symmetrically and equidistantly spaced aroundthe center of rotation and. provide a light structure adapted for highspeeds of rotation and offering very little obstruction to the dischargeof material from the die under such speeds.

r 3 l I claim:

In combination with a, threading device having an externally threadedholder and a conical surfaced die keyed to the end thereof to turntherewith and comprising separated lands with spaces between them forthe discharge of material from the die threads, a rigid cap structureconsisting of a flat externally threaded annular base member on thethreaded end of said holder, an outer plate member of generallytriangular shape with a central opening surrounded by an inner conicalwall diverging from the conical surface of the die and having its edgeat said opening engaging the conical surfaces of the die along a linenear the outer end thereof, sleeve spacers held between said base andplate members at the three corners of said plate member, and

4 rivets passing through said plate and sleeve members and normallyunder tension to hold said base plate and plate members against the endsof said sleeve spacers and in assembled position of the parts to drawsaid edge of said opening tightly onto the outer end of the conical diesurface to center the die on the holder and press the die lands onto thework.

JOHN WATSON.

REFERENCES CITED UNITED STATES PATENTS Name Date Koehler Feb. 6, 1934Number

